Speed-control apparatus



March 24, 1931. A. H, MEARS SPEED CONTROL APPARATUS Filed Oct. '26, 1928 @Mmmm Patented Mar.. 24,

ATNT OFFICE ATHERTQN H. MEARS, G75' PHILADEILEHI, ?.ENNSYLVANIA, ASSIGNOR TO LEEDS @c NRTERUP CDMPANY, F EHILCDELPHEA, PENNSYLVANIA, A. CORFORATION 0F PENNSYLVANIA SPEED-CONTROL .LPPARATUS Application filed @ctober 26, 1222. Serial Ho. 315,152

My invention relates to speed Control apparatus Jfor maintaining constant the speed of mechanism driven by a motor, and more particularly to a governor for maintaining constant the angular velocity olf the rotor of an electric motor used for timing purposes, such as for driving clocks, or tor any purpose where constant speed is desired, under varying conditions oit load on the driving mechanism, oit impressed voltage on the driving motor, or both, and of the general type disclosed in co-pendin application of Leeds, Serial No. 293,7sl0, led duly 18, 1928.

Hitherto the dierential of centrifugal force action upon a governor lyball or equivalent and a restraining force exerted thereon, as by 'a spring, has been utilized to control the speed of an electric motor by actuation of contact mechanism controlling the magnitude of energy supplied thereto. The action of speed governing arrangements utilizing this varying, differential force is adversely influenced by the resulting momentary and variable resistance between contacts. Additionally the small and variable differential :torce was more or less dissipated in overcoming the :triction between relatively moving parts of the switching mechanism. Further as the speed of relative movement ofthe contacts was limited or determined by the low angular velocity of the flyball about its axis, arcing resulte'd introducing further uncontrollable efl'ects to the detriment of precise governing.

In accordance with my invention, a switch member, preferably a contact member, is pivotally supported on an oscillatory member which is in turn supported by a fixed member, and is adapted to be actuated in accordance with theposition of a member carried by the .dyball through the agency of said oscillatory member.

Further and more specifically in accordance with my invention the actuating means for said oscillatory member comprises a cam driven by the motor to be controlled and shaped to give harmonic motion to said member and to insure maximum speed of the contact member at the instant of separation from its co-acting Contact.

Further vand more specifically in accordance with my invention the member carried by the flyball has its center coincident with the axis of rotation ot the governor system and is positioned by the fiyball so that opposing arms of the contact member disposed unequal distances from the plane thereoie are adapted to engage said member due to the movement of the oscillatory member and thereby effect engagement or disengagement of the Contact member with respect to its coacti ng contact.

My invention further resides in features of construction and arrangement ot parts hereinaiter described and claimed.

For an understanding of my invention and some ofthe various forms it may take, reference is to be had to the accompanying drawings in which:

Fig. 1 is an elevational view of the rotatable governor structure.

Fig. 2 is an inverted plan View of stationary structure and elements movablysupported thereon.

Fig. 3 is an elevational view of the structure shown in Fig. 2.

Fig. 4 is a side elevational view showing in part the structure of Figs. 1 and 2 in operativeI relation.

Fig. 5 is a view showing the relation between certain parts of the governing mechamsm.

Referring to Figs. 1/ to 4 inclusive, frame 27 of the governor mechanism is attached to the shaft 1 of a motor M whosespeed is to be controlled., by a set screw or in any other desired manner. The centrifugal member -or lyball 28 which may be weighted in any well known manner, is attached to shaft 29 through arm 28a rotatable in the upper end of bifurcated extension 30 of frame 27 and is freely movable between the head of the adjustable screw 31, which passes -freely through the weighted end thereof, and a stop frame 32 which threadably receives the stop screw 31. Stop frame 32 is secured to frame 27 as by screw 13. A spring 33 passing through opening 11 in hub portion 34 of the frame 27 and through the stop member 32 engages at one end the movable centrifugal element 28', as by pin 12, and at its other end the pin 35 extending downwardly of frame 27. A light frame work 36'movable with the lyball structure 28 passes freely through a slot 14 in a hub portion 37 of frame 27. @n the upper end of hub 37 is secured an eccentric cam 38 which operates in a manner hereinafter described. Frame 36 terminates in a threaded rod portion 39 and has adjustably extending substantially parallel to the axis of rotation of frame 27 clamped thereto a disc 40 concentric with respect to the axis of rotation of-frame 27. y

Referring more specifically to Figs. 2 and 3, a fixed supporting member 44 is adapted to be mounted independently of the motor M and its rotating governor structure 27. Support 44 has pivotally mounted thereon at 43 a frame or switch-supporting member 42. As illustrated in 3 member 42 is pivoted at one end, and at its other end has extending arms 41, spaced as illustrated in Fig. 2, so as to engage the periphery of cam 38 at diametrically opposite points. Member 42 has pivotally mounted thereon at 16 a switch member 47 which is bodily carried thereby. It will be apparent therefore that movement of the member 42 about its pivot 43 will also effect movement of switch member 47 in substantially the same manner. An insulating support 49, connected as by bolt 49a to the fixed support 44, carries a fixed contact 48 which is adapted to be engaged by one end of switch member 47 g Assuming that switch member 47 is in engagement with contact 48 as indicated in Fig. 2, oscillation of member 42 about its pivot 43 will simply cause ro tation of switch member 47 also about substantially the same point and switch member 47 will remain in engagement with contact 48. In the same manner, switch member 47,

if out of engagement with contact 48, would v remain in such position during oscillation of the switch supporting member 42.

If now, however, the end of switch member 47 o n the other side of its pivot 16 were to be kept from rotating with member' 42, as by engagement with some stationary member,.it will be apparent that the contactengaging end of switch member 47 would oscillate through an arc dependent on the movement of member 42, and would therefore intermittently engage contact 48.

Referring to Fig4, apparatus for oscillating member 42 is illustrated.

The periphery of the eccentric 38 is engaged by the lower edges of the downwardly extending arms 41 of the frame or support 42 pivoted at l43. Ihe fixed support 44 carrles a cross arm 45 o f suitable insulating material, the opposite ends of-which are each.

rovided with a binding post 46. Upon the rame 42, which isadapted to be oscillated by cam 38 during energization of motor M, the movable switch member 47, preferably a contact member, 4is suitably electrically connected to a terminal 46, as by conductor 15, and adapted to engage the contact 48 carried by l,block 49. Contact 48 is electrically connected to a terminal 46 as by a conductor 17. Contact member 47 is provided at its opposite end with two actuating arms 50 and 51 disposed in different planes, as shown most clearly in Fig. 5, and adapted to alternately engage the disc 40 during oscillation of frame 42 by cam 38 when disc 4 0 is in predetermined limiting positions. A

'Ihe co-action between the switch actuating arms and member 40 may be best explained by reference to Figs. 2, 3 and 5. Switch member 47 is cut away as at 47a so that the members projecting above disc 40 may not interfere with movement of the disc with respect to the switch actuating arms 50 and 51. Referring more particularly to Fig. 5, disc 40 is shown in its neutral position and lwvill not be engaged by either arm 5() or 51. In case disc 40 should take a lower position. due to increase in speed of motor M, it would be engaged bythe laterally extending arm 51. In the same manner. elevation of disc 40 would put it in the path of arm 50 which would engage the disc, and thereupon actuate the switch member. Member 47 is cut away as indicated in Fig. 3 so that disc 40 will not engage any portion of arm 51 until it has reached a predetermined low position. Switch member 47 may comprise simply a metal stamping having arms 5() and 51 bent at right angles thereto. The operation is' as follows:

Assuming that the speed is below that desired and that the control contact has been made, the angular velocity of the governing system increases until the centrifugal force on the lyball 28 slightly exceeds the restraining force exerted by spring 33. Movement of the liyball towards the head of stop screw 31 carries the disc 40 along the axis of rotation of frame 27 toward the eccentric cam4 38 and into the path of movement of the actuating arm 51. As the'frame 42 is oscillated by cam 38, the arm 51 engages the disc 40. During further movement of frame 42, the Contact arm 47 is rotated about its pivot 16 and the engagement with contact 48 is broken at high velocity.

As a result, by insertion of resistance, the current in the motor is reduced and the speed thereof decreases until the centrifugal force acting on the iyball 28 is less than the restraining force exerted by spring 33, whereupon the flyball moves toward the stop 32 effecting movement of the disc 40 along said axis away from eccentric 38 and into the path 'of movement of the switch actuating arm 50. During oscillation of frame 42, the actuating arm 50 engages disc 40 and is prevented from rotating'with frame 42,. thereupon causing the contact arm 47 to rotate about its pivot 16 and into engagement with fixed contact 48, whereupon the current inthe motor is in- T Cil momie creased and the cycle of operation is repeated.

Cam 38 is particularly designed in the present instance to give harmonic motion to the oscillatory member 42, and therefore to the switch member l? which is bodily carried thereby. ln the interruption of current by separation of mechanical contacts, it is essential that the separation be efected by comparatively high speed so as to avoid excessive areingl and corrosion of the contact members. lt is also essential that the contacts be both positively made and broken so that the switch resistance will remain substantially constant.

, ly so designing cam 38 that-harmonic motion is imparted to the switch supporting member ft2, the relation ot the cam with respect to switch member l? may be so adjusted that separation of the co-acting contacts is effected during maximum speed of switch member el?. Switch member 47 therefore, When'in engagement with disc 40, moves in harmonic motion between its two limiting positions, and effects interruption, or closure, ot the circuit its position of maximum velocity. lt will be understood, however, that cam 38 may have such-design that pure liarnionic motion is not imparted to member d2. llor example the cam may have any design which will impart to member l2 comparatively slovv motion at its limits olf travel and relatively East motion between such limits, i. e. when contact is made or broken.

Although the dravvin gs show cam 38 driven directlyby motor lil, Whose speed is to controlled, Will be understood that suon cam may be driven independently by other means. rl`lne essential requirement is that the Jforce driving the cam 38 be very much greater than the torce actuating the disc 40, so that the actual switching operation will not be edected by the relatively delicate centrifugal mechanism its-ell, but by some substant1al force which controlled merely by the posit1on of the centrifugal means.

' As the movement of the switching mechanism of this governor may be although not necessarily harmonic in character, due to the design of the eccentric cam, for brevity inthe above specification and appended claims it 1s termed harmonic l/Vbat l claim is:

l. Speed control apparatus comprising structure rotatable in response to the velocity to be controlled, a member carried by said structure and movable along the axis of rotation of said structure in accordance ivith variations in said velocity, a contact member having portions adapted tov be moved at substantially right angles to said axis into engagement vvith said hrst-named member, and means operable independently of said lirstnamed member 'for imparting such movement to said contact member.

2. Speed control apparatus comprising structure rotatable in response to the velocity to be controlled, a member carried by said structure 'and movable along the axis of rotation of said structure in accordance With variations in said velocity, an oscillatory support mounted independently of said structure, and a Contact member pivotally carri-ed by said support and adapted to be actuated by engagement with said irstf-named member.

3. Speed control apparatus comprising structure rotatable in response to the velocity to be controlled, a member carried by said structure and movable along the axis of rotation of said structure in accordance With variations in said velocity, an oscillatory support mounted independently of said structure, a contact member pivotally carried by said support, and abutments carried by. said contact member spaced unequal distances therefrom along said axis so that they may engage said first-named member in dillerent positions thereof.

el. Speed control apparatus comprising structure rotatable in response to the velocity to be controlled, a member carried by said structure and movable along the aXis oit rotation of said structure in accordance with variations in said velocity, a hired support, an oscillatory member pivotally secured to said support, and a switch member pivotally carried by said oscillatory member having portions adapted to be brought into engagement with said first-named member.

5. Speed control apparatus comprising structure rotatable in response to the velocity to be controlled, a member carried by said structure and movable to different positions along the axis of rotation of said structure in accordance with variations in said velocity, a liXed support,- a member pivotally secured to said support, means operable to impart oscillatory movement to said pivoted member, and a switch member pivotally connected to and bodily movable with said oscillatory member and having portions engageable selectively with said first-named member upon movement or the latter from one of said positions to the other.

6. Speed control apparatus comprising structure rotatable in response tothe velocity to be controlled, a member carried by said structure and movable to different positions along the anis of rotation of said structure in accordance with variations in said velocity, a ixed support, a member pivotally mounted on said support, means for imparting harmonic oscillatory movement to said pivoted member, a relatively stationary contact, and a contact member bodily carried by and pivoted to said pivoted member and having portions adapted to engage said first-named member selectively upon movement of the latter from one of said positions to the other.

7. Speed control apparatus comprising structure rotatable in response to the velocity to be controlled, a member carried by said structure and movable to different positions along the axis of rotation of said structure in accordance with variations in said velocity, an oscillatory support mounted independently of said structure, and a Contact member pivotally carried by said support and engageable selectively with said first-named member upon movement of the latter from one of said positions-to the other.

8. In speed control apparatus, centrifugal governor means rotatable about a given axis, a member supported for oscillatorymovement and provided with elements, means for imparting such movement to said member during operation of said apparatus, and a second member disposed substantially at said axis and movable longitudinally thereof into selective engagement with said elements, said governor means operable to eect engagement of said second member with certain of said elements at certain speed conditions and with certain other of said elements at speed conditions ditlerent from said certain speed conditions. v

ATHERTON H. MEARS.

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